There are a multitude of different personal cooling devices. They generally fall into three classifications; 1) those devices that supply a mist of fluid, 2) those devices with only a fan and 3) those that have misting capabilities with some form of fan device.
In respect to the development of those devices which supply a mist of fluid, it can easily be seen in the prior art disclosed that the concept is not unique to this invention. The vessel that is used to contain the fluid during pressurization can be in many shapes, from square (U.S. Pat. No. 5,622,056) to cylindrical (U.S. Pat. No. 5,775,590) to product shaped (U.S. Des Pat. D439966) and the pressurization method can either come from a pump, manually driven (U.S. Pat. No. 6,371,388) or motor driven (U.S. Pat. No. 8,016,270), that pressurizes the fluid or that inflates a bladder (U.S. Pat. No. 5,622,056), that when pressurized or inflated thereby increases the volume of air in the vessel, thereby creating pressure according to Boyle's Law. Due to this pressure, when the fluid is released to the atmosphere, through a restrictive throttling where it is atomized, heat is extracted heat but not exchanged. This process is also known as the Joule-Thompson effect or evaporative cooling. It is obvious that motor driven pumps are either subject to increased weight for pump mechanism and power sources or failure of power when the device is most needed.
Personal fans have been disclosed in many different shapes but all have a basic design whereby fan blades are attached to a central hub and air is exhausted therethrough. The purpose is primarily cooling through the evaporation of moisture on one's skin through an adiabatic process. (U.S. Pat. Nos. 6,155,782 and 5,667,732)
It has also been disclosed by prior art that fans have been used to disperse the air that has been cooled through evaporative cooling. This convective cooling principle works where air, that has been cooled through evaporative cooling now flows over surfaces of greater heat, thereby cooling those surfaces. The rate of heat loss of a body is proportional to the difference in temperatures between the body and its surrounding as by Newton. Prior art has several methods of dispersing this air cooled through evaporative cooling. U.S. Pat. No. 2,079,117 details fluid being dispensed from a centralized hub along the blades of the fan. The problem with this approach is that the fluid will coalesce along the blades as the is the air pressure over the blades is much higher than the air immediately in front of the blade, causing a vacuum effect, very similar to the concept that propels sailboats going upwind. Mist will form up along the edges of the blades and will whip off circumferentially negating the cooling effects of the fluid. Other disclosures have the fluid emanate from behind the fan structure (U.S. Pat. No. 4,338,495)) or where the misting device is placed in front of the fan at varying distances away from the actual fan itself (U.S. Pat. No. 8,016,270 and U.S. Pat. No. 6,371,388). Both devices suffer from a deficient design that does not optimal utilize the cooling effect. Being behind the blade causes the blade to intersect the fluid stream causing drips and those devices that place the misting device in front of the fan suffer from the centripetal forces caused by the rotation of the air about the center of the fan hub. The main stream of the fluid flow from the fan rotates about the central axis of the fan whereby the fluid streams “rifle” away from the fan. This “rifling” of heavy moisture laden air causes the mist to be concentrated into a narrow beam of cooling.
What is needed then is a device which has the ability to produce a cooling effect upon people through the use of evaporative and convectional cooling which does not have any of the negative attributes of the prior art.
What is needed is a device that combines the best attributes of convective cooling and the best attributes of evaporative cooling effect while eliminating the problems associated with the prior examples of the art and then let the operator choose the desired effect.